A standard spinning operation has three main subsystems: the roving or fly frame, the ring-spinning frame, and the bobbin cleaner. The roving is reduced in two stages to yarn in the fly and ring frames, and in the cleaner the bobbins are stripped of any scraps of roving that remain attached to them so they can be recirculated to the fly frame.
Typically an annular track-type conveyor system is provided from which the bobbins hang as they move from subsystem to subsystem. Since, however, the capacities of the various subsystems invariably are different and even vary somewhat, it is necessary to provide some storage arrangement so that when, for instance, the roving subsystem outputs too many roving bobbins, some of them can be stored until the ring-spinner has some extra capacity and can handle them. Similarly the cleaner typically only works on a single bobbin at a time, albeit very quickly, so that it cannot deal with the bobbins that arrive in batches or so-called trains. Thus it is necessary to provide a shunting arrangement and a storage facility between each subsystem and the next one.
In European patent publication 401,828 of S. Kidana et al (based on a Japanese priority of 09 Jun. 1989) and German 3,601,832 of H. Guttler (filed in Germany 22 Jan. 1986) an annular track system is shown with movement in a single direction. U.S. Pat. No. 5,148,665 and equivalent European patent publication 454,897 of S. Kidani (based on a Japanese priority of 28 Apr. 1990) have storage shunts that are fed from one end with two-way traffic into and out of them. This open rail system can have one or more tracks as described in European patent publication 431,268 of M. Erni (based on a Swiss priority of 18 Oct. 1989) and three different storage systems. Closed systems normally have the advantage over open systems that, due to the one-way movement of the bobbin-holding carriages, a single track can be used rather than the more complex two-track arrangement of the open storage systems.
Both the flyers and the ring spinners need a supply of fresh spools, loaded in the one case and empty in the other, as they work. This resupply typically takes place batch-wise so that the storage or buffer systems are used as described in German 2,227,105 of K. Klein (filed in Germany 03 Jun. 1972). This single-track system has storage areas that take full and empty bobbins, but no provision is made for cleaning the bobbins.
Closed storage systems such as described in Japanese 61-215,724 have two or more separate storage systems when they are provided with a bobbin cleaner. Such an arrangement is further described in the Zinser in-house publication "Konzept der Ringspinnerei" (concept of ring spinning).
The discontinuous supply and demand of bobbins and/or sleeves in all three subsystems thus normally requires three different buffer/storage systems. Thus between the flyers and the ring-spinning machines there is normally a storage facility with a somewhat larger capacity than the ones between the ring-spinners and the cleaner and between the cleaner and the flyers. Both empty and full bobbins must be stored in the storage unit between the flyers and the ring spinners, while the other two buffer-storage areas only hold essentially empty bobbins. Since a flyer subsystem normally does not have more than 120 spindles, the storage facilities associated therewith do not have to have much larger capacity.
There is therefore a tradeoff in designing such systems between, on the one hand, providing the largest possible buffers and thereby going to considerable expense and taking up considerable space and, on the other hand, minimizing buffer size, cost, and space requirements and thereby running the risk of putting a bottleneck in the production facility.